Bain Capital, which helped to take the largest U.S. office supply public more than two decades ago, did not immediately respond to a request seeking comment. Staples declined to comment.

The discussions have been preliminary thus far and the earliest an actual offer could come would be late this year, the sources told Fortune.

The report came less than a month after Staples cut its profit and sales forecasts for the year, citing slower growth in the U.S. economy and continued weakness in Europe.

Staples shares, which have lost about a quarter of their value over the past six months, rose 3.6 percent to close at $11.96 Thursday on Nasdaq. They rose further in after-hours trading.

The company has a market cap of about $8 billion.

Staples, once regarded by Wall Street as the best of the publicly listed office supply chains, has suffered from sluggish sales in the past year as European demand remains weak and U.S. business customers spend less on non-essential items.

Rivals Office Depot and OfficeMax have also found it harder to sustain or boost sales as the office supply industry faces strong competition from mass merchants, drugstores, dollar stores and online giant Amazon Inc.